The invention relates to a device for making potable water out of water contaminated by a.o. chemical, biological and nuclear pollutants, as well as by pathogenic bacteria, viruses, and normal solid particles. The provided by a perforated plate filter for filtering out the coarse pollutants. The plate filter is connected to a finer filter, for retaining the finer particles. The latter is in turn coupled to an ultrafilter, for removing the remainder of the undissolved materials, including colloids, bacteria and viruses. This is in turn followed by a hyperfilter through which the water is forced against the osmotic pressure and in which the greater part of the dissolved materials, like heavy metals, phenolics, haloforms, pesticides and radioactive compounds, stays behind. This is in turn, followed by an activated carbon filter for removing the remainder of any highly toxic chemicals.
Such a device is known from "Innovatie", Volume 14, No. 62, Dec. 1984.
For these devices it is required that the output of potable water remain constant for a long period. Owing to contamination of the ultrafilter, the output will slowly decrease, which drawback can be overcome by installing a buffertank. However, a buffertank between the ultrafilter and the hyperfilter (called reverse osmosis filter as well), considerably increases the volume of the device which mostly has to be transportable, whereas moreover the danger exists of a renewed infection by bacteria and viruses, which of course is undesirable.